Core Architecture#

The system follows a modular architecture with these main components:

1. Consensus Layer: Proof-of-Stake with validator selection
2. Networking Layer: P2P communication between nodes
3. Execution Layer: Smart contract virtual machine
4. Data Layer: Blockchain storage and state management
5. Interface Layer: CLI and REST API

class BlockchainNode:
    def __init__(self, host, p2p_port, api_port):
        self.blockchain = Blockchain()
        self.mempool = Mempool()
        self.wallet = Wallet(self)
        self.p2p_network = P2PNetwork(host, p2p_port, self.blockchain)

Key Innovations#

class ProofOfStake:
    def select_validator(self, seed):
        total_stake = sum(self.validators.values())
        vrf = VRF(private_key=self.staking_contract)
        proof = vrf.prove(seed)
        random_value = int.from_bytes(proof, 'big') % total_stake
        # Stake-weighted selection...

class Wallet:
    def _drive_encryption_key(self):
        kdf = PBKDF2HMAC(
            algorithm=hashes.SHA512(),
            length=32,
            salt=salt,
            iterations=100000,
            backend=default_backend()
        )
        return base64.urlsafe_b64encode(kdf.derive(password.encode()))

class SmartContractVM:
    GAS_COSTS = {
        'ADD': 3,
        'SUB': 3,
        'MUL': 5,
        'SSTORE': 200,
        # ... other opcodes
    }
    
    def execute(self, tx, block_number, timestamp):
        signal.alarm(5)  # 5-second timeout
        try:
            # Execute contract code
            # ...
        finally:
            signal.alarm(0)

Performance Optimization#

1. Block Cache: LRU caching of recent blocks
2. Batch Processing: Bulk transaction saving
3. Compact Blocks: Reduced bandwidth usage
4. State Pruning: Periodic state cleanup

class Blockchain:
    def __init__(self):
        self.block_cache = LRUCache(capacity=100)
        
    def add_block(self, block):
        self.block_cache.put(block.index, block)
        # ...

Networking Protocol#

The P2P layer implements:

• Message signing/verification
• Compact block propagation
• Transaction gossiping
• Peer discovery

class P2PNetwork:
    def broadcast_block(self, block):
        if len(block.transactions) > 10:
            self.broadcast_message({
                "type": "compact_block",
                "data": block.to_compact()
            })
        else:
            # Full block broadcast

Lessons Learned#

1. State Management is Hard: Tracking balances, nonces, and contract storage requires careful synchronization.
2. Security Tradeoffs: Every convenience feature (like auto-loading wallets) creates potential attack vectors.
3. Testing is Crucial: Blockchain systems need extensive test coverage due to their irreversible nature.
4. Document Early: Complex interactions between components become unmanageable without good documentation.

Future Work#

1. Sharding support
2. Cross-chain interoperability
3. Zero-knowledge proofs
4. Formal verification of smart contracts

The complete source code is available on GitHub. I welcome contributions and feedback from the community!